The influence of climate on pool inception in boreal fens

Fens are one of the two most important peatland types of the boreal biome. The fen surface is often made of contrasted microenvironments, pools and strings, distributed in a geometric arrangement known as patterned fen. The fens are under the influence of varying water regimes causing the formation of pools, a process that we named aqualysis. The term refers to the physical degradation of the vegetation cover under the influence of water ponding. It is proposed here that pool inception is among a set of differential responses of peatland ecosystems to changes in hydrology caused by climate. In this study, we have evaluated the influence of climate on pool inception using the spatiotemporal distribution of trees found dead in pools of four boreal fens of northwestern Quebec. Tree-ring dating of tree mortality allowed the determination of the most recent and synchronized periods of pool formation in the studied fens. Most trees died over the last centuries, particularly after 1750 AD. The demographic pattern of tree establishment and mortality highlights a climatic forcing linked to the Little Ice Age oscillation opposing less humid events facilitating tree colonization succeeded by more humid events causing massive tree death and pool inception. We conclude that peatland aqualysis is among the processes controlled by climate contributing to the dynamics of patterned fens through pool formation.

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Paleoenvironmental records of water level and climatic changes from the middle to late holocene at a Lake Erie coastal wetland, Ontario, Canada

Quaternary Research ◽

10.1016/j.yqres.2005.08.021 ◽

2006 ◽

Vol 65 (1) ◽

pp. 33-43 ◽

Cited By ~ 18

Author(s):

Sarah A. Finkelstein ◽

Anthony M. Davis

Keyword(s):

Water Level ◽

Plant Communities ◽

Little Ice Age ◽

Lake Erie ◽

Coastal Wetland ◽

Climatic Changes ◽

Ice Age ◽

Climatic Forcing ◽

Site Water ◽

Northern Shore

AbstractPollen and diatom assemblages, and peat stratigraphies, from a coastal wetland on the northern shore of Lake Erie were used to analyze water level and climatic changes since the middle Holocene and their effects on wetland plant communities. Peat deposition began 4700 cal yr B.P. during the Nipissing II transgression, which was driven by isostatic rebound. At that time, a diatom-rich wild rice marsh existed at the site. Water level dropped at the end of the Nipissing rise at least 2 m within 200 yr, leading to the development of shallower-water plant communities and an environment too dry for most diatoms to persist. The sharp decline in water level was probably driven primarily by outlet incision, but climate likely played some role. The paleoecological records provide evidence for post-Nipissing century-scale transgressions occurring around 2300, 1160, 700 and 450 cal yr B.P. The chronology for these transgressions correlates with other studies from the region and implies climatic forcing. Peat inception in shallow sloughs across part of the study area around 700 cal yr B.P. coincides with the Little Ice Age. These records, considered alongside others from the region, suggest that the Little Ice Age may have resulted in a wetter climate across the eastern Great Lakes region.

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Inversion results appended with estimates from vegetation changes in assessment of Ground Surface Temperatures for the Amazon Region, Brazil

International Journal of Terrestrial Heat Flow and Applications ◽

10.31214/ijthfa.v4i1.63 ◽

2021 ◽

Vol 4 (1) ◽

pp. 140-147

Author(s):

Valiya Hamza ◽

Fábio Vieira ◽

Suze Guimaraes ◽

Elizabeth Pimentel

Keyword(s):

Vegetation Cover ◽

Little Ice Age ◽

Ground Surface ◽

Remote Sensing Data ◽

Functional Space ◽

Amazon Region ◽

Ice Age ◽

Vegetation Changes ◽

Inverse Models ◽

Borehole Temperature

Estimates have been made of ground surface temperature (GST) variations for 25 localities in the region of Manaus (province of Amazon in Brazil) making use of both forward and inverse models. The work is based on analysis of borehole temperature logs as well as remote sensing data concerning changes in vegetation cover. Results of functional space inversion (FSI) of borehole temperature data reveal the occurrence of a cooling event, with a decrease in temperature of slightly less than 1oC, for the period of 1600 to 1850 AD. This episode coincides roughly with the period of “little ice age” in the southern hemisphere. It was followed by a warming event, with magnitudes varying from 2 to 3oC, that lasted until recent times. Integration of these results with estimates based on changes in normalized index of vegetation cover (NVDI) of the last decade points to continuation of climate warming over the last decade. This event is found to be prominent in areas of deforestation in central parts of the Amazon region.

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Little Ice Age glacial activity in Strathcona Provincial Park, Vancouver Island, British Columbia, Canada

Canadian Journal of Earth Sciences ◽

10.1139/e03-102 ◽

2004 ◽

Vol 41 (3) ◽

pp. 285-297 ◽

Cited By ~ 29

Author(s):

Dave H Lewis ◽

Dan J Smith

Keyword(s):

British Columbia ◽

Little Ice Age ◽

Vancouver Island ◽

Ice Age ◽

Canadian Rocky Mountains ◽

Climatic Forcing ◽

Climate Conditions ◽

The Pacific ◽

History Of ◽

Provincial Park

Dendroglaciological and lichenometric techniques are used to establish the Little Ice Age (LIA) history of two glaciers (Colonel Foster and Septimus) in Strathcona Provincial Park, Vancouver Island, British Columbia. Our lichenometric investigations were preceded by the development of a locally calibrated Rhizocarpon geographicum growth curve (17081998 A.D.). Documentation of a 34-year ecesis interval for both trees and lichen greatly reduces one of the main uncertainties in using geobotanical methods for dating LIA landforms. The moraine dates provided, therefore, give a good approximation of the shift in climate conditions that lead to the retreat of the glaciers and subsequent moraine stabilization. Geobotanical evidence records three synchronous episodes of LIA moraine deposition at both glaciers: two prominent moraines at each site are dated to the early 1700s and late 1800s, with a third, smaller moraine dated to the mid 1930s. Moraines deposited prior to 1397 A.D. were also recorded at Colonel Foster Glacier; however, precise dating of these moraines was not possible. The moraine records from Strathcona Provincial Park suggest two possible modes of glacier response: (i) synchronous responses to larger-scale climatic forcing, and (ii) asynchronous responses to local factors such as microclimate, topography, and glacier geometry. The Vancouver Island LIA record was evaluated in the context of LIA results from the Pacific North American (PNA) Cordillera. It compares well with regional moraine records from coastal British Columbia, Washington, Alaska, and the Canadian Rocky Mountains, suggesting a regional response of PNA glaciers to climate change associated with the LIA.

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Greenhouses, hot water bottles, cycles and the future of New Zealand climate

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.2009.71.2772 ◽

2009 ◽

pp. 61-67

Author(s):

W.P. De Lange

Keyword(s):

New Zealand ◽

Thermal Energy ◽

Infrared Radiation ◽

Little Ice Age ◽

Hot Water ◽

Ice Age ◽

The Sun ◽

Weather Patterns ◽

Time Periods ◽

Almost All

The Greenhouse Effect acts to slow the escape of infrared radiation to space, and hence warms the atmosphere. The oceans derive almost all of their thermal energy from the sun, and none from infrared radiation in the atmosphere. The thermal energy stored by the oceans is transported globally and released after a range of different time periods. The release of thermal energy from the oceans modifies the behaviour of atmospheric circulation, and hence varies climate. Based on ocean behaviour, New Zealand can expect weather patterns similar to those from 1890-1922 and another Little Ice Age may develop this century.

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